Systems and methods for scale calibration

ABSTRACT

Systems and methods for scale calibration. One example embodiment provides a system for calibrating a scale. The system may generally include an actuator for applying force to a platform of the medical scale, and an electronic processor communicatively coupled to the actuator. The electronic processor may be configured to control an actuator to apply, for a first interval, a first applied force having a first value greater than a target force value, and control the actuator to apply, for a second interval, a second applied force having a second value substantially equal to the target force value.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of and claims the benefit ofthe filing date of co-pending U.S. patent application Ser. No.16/924,655, filed Jul. 9, 2020, which claims priority to U.S.Provisional Patent Application No. 62/871,870, filed Jul. 9, 2019.

FIELD

The present application relates to systems and methods for calibratingscales, for example, medical scales, and, more particularly, tocontrolling a calibration device, which applies force to scales tocalibrate and test the scales.

SUMMARY

Scales are used in healthcare environments (for example, facilities withboth critical care and primary care) to measure the weight of a patient.A weight of the patient can provide important or useful information to,for example, detect fluid retention, calculate proper medicationdosages, screen for malnutrition, etc. It is therefore desirable formedical scales to provide accurate weight measurements to healthcareprofessionals and other users.

Because medical scales are used to provide information for patient care,medical scales may be calibrated regularly or from time to time asdeemed necessary. Other types of scales are also relied upon foraccurate measurements and may, therefore, be regularly calibrated.Typical calibration methods use reference weights, and the calibrationprocess can be expensive (for example, about 35-90% of the cost of a newscale per calibration), labor intensive and time-consuming, especiallyfor a facility with numerous scales.

Because weight is a measure of the force of gravity on the object beingweighed, the measurement of weight varies with the gravity for thelocation where the weighing occurs. Scales must therefore be calibratedin the field where they are deployed.

Calibration reference weights must be carefully maintained and aredifficult and expensive to transport to the location of each scale to becalibrated. Furthermore, calibration with reference weights requiresplacing and removing weights on the scale platform multiple times foreach set point across a calibration range. For example, a scale may becalibrated at 100 pounds, 200 pounds, 300 pounds, and 400 pounds. Therepeated moving of reference weights (e.g., weighing 50 pounds each)during this process may present a risk of damage to scale componentsand/or other items in the area, including the scale calibratorsthemselves.

Calibrating a scale using calibration reference weights limits the uppercalibration range to the amount of weights that can be transported bycalibrator. For example, a scale cannot be calibrated at the 400 poundlevel using reference weights if only 300 pounds of reference weightsare present. In addition, the granularity of the calibration is limitedby the types and numbers of calibration reference weights transported bya calibrator. For example, to calibrate in one, ten, or five poundincrements would require transporting and caring for a sufficientquantity of those reference weight sizes in addition to the larger sizesrequired to calibrate at higher (for example, 100 pound) increments.

To potentially address these and other concerns, calibration deviceshave been developed. Such devices apply force directly to a platform ofa scale to simulate a weight for use in calibrating and testing thescale. Some scale calibration devices apply an intended calibrationforce for a period of time.

During the calibration process, it is important that the intendedcalibration force remains constant in order to accurately calibrate thescale. However, some calibration devices exhibit a decay over time inthe exerted force on the scale. This decay may be due to flexing of thematerials comprising the calibration device, the scale, etc. The decayin exerted pressure can lead to inaccurate calibration or testing of ascale. In some instances, the decay is relatively rapid. However,waiting for the decay to decrease to a useful level for each set pointin a calibration range can significantly increase the time required fora scale calibration, lead to errors in calibration, or both.

Accordingly, independent embodiments described herein provide, amongother things, systems and methods for calibration of scales, and suchsystems or methods may be at least partially automated.

One independent embodiment provides a method for calibrating a scale,such as, for example, a medical scale. The method may generally includeapplying (e.g., controlling an actuator to apply), for a first interval,a first applied force having a first value greater than a target forcevalue; and, after the first interval, applying, for a second interval, asecond applied force having a second value substantially equal to thetarget force value.

Another independent embodiment provides a system for calibrating ascale. The system may generally include an actuator for applying forceto a platform of the medical scale, and an electronic processorcommunicatively coupled to the actuator. The electronic processor may beconfigured to control an actuator to apply, for a first interval, afirst applied force having a first value greater than a target forcevalue, and control the actuator to apply, for a second interval, asecond applied force having a second value substantially equal to thetarget force value.

In yet another independent embodiment, a method for calibrating a scalemay generally include controlling the actuator to apply, for acalibration interval, an applied force having an applied force valuesubstantially equal to a target force value, during the calibrationinterval, receiving, from a load sensing device (e.g., a load cell), anapplied force value for the applied force, when the applied force valueis less than the target force value by a first threshold, controllingthe actuator to increase the second applied force to the target forcevalue, and, when the applied force value is greater than the targetforce value by a second threshold, controlling the actuator to reducethe second applied force to the target force value.

In a further independent embodiment, a method for calibrating a scalemay generally include controlling an actuator to apply, for a firstinterval, a first applied force having a first value greater than atarget force value, controlling the actuator to apply, for a secondinterval, a second applied force having a second value substantiallyequal to the target force value, during the second interval, receiving,from a load sensing device (e.g., a load cell), an applied force valuefor the second applied force, when the applied force value is less thanthe target force value by a first threshold, controlling the actuator toincrease the second applied force to the target force value, and, whenthe applied force value is greater than the target force value by asecond threshold, controlling the actuator to reduce the second appliedforce to the target force value.

In another embodiment, a system for calibrating a scale may generallyinclude a human machine interface; an actuator for applying force to aplatform of the medical scale; and an electronic processorcommunicatively coupled to the human machine interface and the actuator.The electronic processor may be configured to receive a target forcevalue by receiving a user input via the human machine interface, inresponse to receiving the user input, control the actuator to apply, fora pre-calibration interval, a preliminary applied force having apreliminary value, when the pre-calibration interval has expired,disengage the actuator, display, via the human machine interface, a userprompt requesting a confirmation command, and, in response to receivingthe confirmation command, control an actuator to apply, for a firstinterval, a first applied force having a first value greater than thetarget force value, and control the actuator to apply, for a secondinterval, a second applied force having a second value substantiallyequal to the target force value.

Using such embodiments, scales, such as medical scales, may, forexample, be calibrated more quickly, accurately, etc.

Other independent aspects of the invention may become apparent byconsideration of the detailed description, claims, and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a scale calibration system, according tosome independent embodiments.

FIG. 2 is a block diagram of an electronic controller of the system ofFIG. 1 according to one embodiment.

FIG. 3 depicts an example embodiment of the scale calibration device ofthe system of FIG. 1 .

FIG. 4 is a block diagram of a display of the system of FIG. 1 accordingto one embodiment.

FIG. 5 is a flowchart of a method of using a calibration engine of theelectronic controller of FIG. 2 to receive a target force value andcontrol an actuator based on the target force value according to oneembodiment.

FIG. 6 is an illustration of a user interface for calibrating a scaleaccording to one embodiment.

FIGS. 7-9 are line graphs illustrating the rate of change experienced bya load cell during a calibration sequence.

DETAILED DESCRIPTION

Before any independent embodiments are explained in detail, it is to beunderstood that the embodiments presented herein are not limited intheir application to the details of construction and the arrangement ofcomponents set forth in the following description or illustrated in thefollowing drawings. The independent embodiments presented herein arecapable of being practiced or of being carried out in various ways.Also, it is to be understood that the phraseology and terminology usedherein is for the purpose of description and should not be regarded aslimiting.

The use of “including,” “comprising,” or “having” and variations thereofherein is meant to encompass the items listed thereafter and equivalentsthereof as well as additional items. The terms “connected” and “coupled”are used broadly and encompass both direct and indirect mounting,connecting, and coupling. Further, “connected” and “coupled” are notrestricted to physical or mechanical connections or couplings, and caninclude electrical connections or couplings, whether direct or indirect.Also, electronic communications and notifications may be performed usingany known means including wired connections, wireless connections, etc.

Relative terminology, such as, for example, “about,” “approximately,”“substantially,” etc., used in connection with a quantity or conditionwould be understood by those of ordinary skill to be inclusive of thestated value or condition and has the meaning dictated by the context(for example, the term includes at least the degree of error associatedwith the measurement of, tolerances (e.g., manufacturing, assembly, use,etc.) associated with the particular value or condition, etc.). Suchterminology should also be considered as disclosing the range defined bythe absolute values of the two endpoints. For example, the expression“from about 2 to about 4” also discloses the range “from 2 to 4.” Therelative terminology may refer to plus or minus a percentage (e.g., 1%,5%, 10% or more) of an indicated value.

Also, the functionality described herein as being performed by onecomponent may be performed by multiple components in a distributedmanner. Likewise, functionality performed by multiple components may beconsolidated and performed by a single component. Similarly, a componentdescribed as performing particular functionality may also performadditional functionality not described herein. For example, a device orstructure that is “configured” in a certain way is configured in atleast that way but may also be configured in ways that are not listed.

It should also be noted that a plurality of hardware and software-baseddevices, as well as a plurality of different structural components maybe used to implement the embodiments. In addition, it should beunderstood that embodiments may include hardware, software, andelectronic components or modules that, for purposes of discussion, maybe illustrated and described as if the majority of the components wereimplemented solely in hardware. However, one of ordinary skill in theart, and based on a reading of this detailed description, wouldrecognize that, in at least one embodiment, the electronic-based aspectsof the invention may be implemented in software (for example, stored onnon-transitory computer-readable medium) executable by one or moreprocessors. As such, it should be noted that a plurality of hardware andsoftware-based devices, as well as a plurality of different structuralcomponents may be utilized to implement the invention. For example,“control units” and “controllers” described in the specification caninclude one or more processors, one or more memory modules includingnon-transitory computer-readable medium, one or more input/outputinterfaces, and various connections (for example, a system bus)connecting the components.

For ease of description, some or all of the example systems presentedherein are illustrated with a single exemplar of each of its componentparts. Some examples may not describe or illustrate all components ofthe systems. Other example embodiments may include more or fewer of eachof the illustrated components, may combine some components, or mayinclude additional or alternative components.

FIG. 1 illustrates an example independent embodiment of a scalecalibration system 100 for calibrating a scale (for example, a medicalscale). In the example illustrated, the system 100 includes anelectronic controller 105 and a scale calibration device 110. The scalecalibration device 110 may be similar to the devices illustrated anddescribed in U.S. patent application Ser. No. 16/145,276, filed Sep. 28,2018, the entire contents of which are hereby incorporated by reference.

The illustrated components, along with other various modules andcomponents, are coupled to each other by or through one or more controlor data buses that enable communication therebetween. The use of controland data buses for the interconnection between and exchange ofinformation among the various modules and components would be apparentto a person skilled in the art in view of the description providedherein.

The scale calibration device 110 is configured to receive commands fromthe electronic controller 105 and to apply a force, based on thereceived commands, to a scale 115 to be calibrated. The scalecalibration device 110 is communicatively connected to the electroniccontroller 105 via one or more communication links and, in this example,via a wired connection; however, in some embodiments, the scalecalibration device 110 may be communicatively connected over a wirelessnetwork or a short-range wireless connection.

FIG. 2 is a block diagram of the electronic controller 105 of the systemof FIG. 1 . The electronic controller 105 includes a plurality ofelectrical and electronic components that provide power, operationcontrol, and protection to the components and modules within theelectronic controller 105. The illustrated electronic controller 105includes, among other things, an electronic processor 205 (such as aprogrammable electronic microprocessor, microcontroller, or similardevice), a memory 210, a first communication interface 215, and adisplay 220. In some embodiments, the electronic controller 105 is acomputing device, such as a laptop computer, a tablet computer, a smartphone, a smart watch, etc.

The memory 210 is, for example, a non-transitory, machine-readablememory. The first communication interface 215 is communicativelyconnected to the scale calibration device 110. The electronic processor205 is communicatively connected to the memory 210, and the firstcommunication interface 215. The memory 210 includes a calibrationengine 225 (for example, software or a set of computer-readableinstructions that determines commands to be sent to the scalecalibration device 110).

The electronic controller 105 may be implemented in several independentcontrollers each configured to perform specific functions orsub-functions. Additionally, the electronic controller 105 may containsub-modules that include additional electronic processors, memory, orapplication specific integrated circuits (ASICs) for handlingcommunication functions, processing of signals, and application of themethods listed below. In other embodiments, the electronic controller105 includes additional, fewer, or different components.

The first communication interface 215 coordinates the communication ofinformation between the electronic processor 205 and the scalecalibration device 110. In the example illustrated, information receivedfrom the display 220 is provided to the electronic processor 205 toassist in determining what commands will be executed by the calibrationengine 225. The determined commands are then provided from theelectronic processor 205 to the first communication interface 215 wherethe commands are transmitted to the scale calibration device 110. Inother embodiments, the information received from the display 220 may beprovided without a display and may be, for example, transmitted from aremote server where the information is stored in a storage medium, suchas a database.

The memory 210 can include one or more non-transitory machine-readablemedia, and includes a program storage area and a data storage area. Theprogram storage area and the data storage area can include combinationsof different types of memory, as described herein. In some embodiments,data is stored in a non-volatile random-access memory (NVRAM) of thememory 210. Furthermore, in some embodiments, the memory 210 storespredetermined factors with which to adjust commands, such as apredetermined gravity factor as well as other factors that may be usedto manipulate or alter the determined commands for the scale calibrationdevice 110 (as described in more detail below).

FIG. 3 illustrates an example construction of the system 100. In theillustrated construction, the scale calibration device 110 includes acontrol box 305, a force applying mechanism 306 (e.g., a motor 307 andan actuator 310), a load cell 315, a wired connection 320 between theelectronic controller 105 and the scale calibration device 110, and abase surface 325 for a scale (not shown) to rest on during testing andcalibration. In the illustrated construction, the electronic controller105 is a laptop computer communicatively connected, via a wiredconnection (as illustrated), to the scale calibration device 110.However, in other embodiments, the electronic controller 105 may beanother type of computing device and/or may be coupled wirelessly withthe scale calibration device 110.

The control box 305 is communicatively coupled to the electroniccontroller 105 and includes one or more electronic components configuredto control the force applying mechanism 306 to apply a force (e.g., on ascale to be tested or calibrated according to the methods describedherein). In the illustrated construction, the load cell 315 is supportedat the end of the actuator 310 to measure the applied force of the forceapplying mechanism 306 (e.g., on a scale). In some embodiments, a loadsensing device or a force measurement mechanism other than a load cellmay be used. The control box 305 receives commands from the electroniccontroller 105 and causes the force applying mechanism 306 to apply thespecified force (e.g., by controlling the motor 307 to move the actuator310 downwardly).

In the illustrated construction, the force applying mechanism 306includes the motor 307 (e.g., a stepper motor, a servo motor, etc.) andthe actuator 310 (e.g., including an internal gear set). In otherembodiments, an alternate force applying mechanism (e.g., a hydrauliccylinder assembly) may be used. The force is applied to the scale byactivating the force applying mechanism 306 to establish the specifiedlevel of force (e.g., as a proxy for a test weight) on the scale. Thescale calibration device 110 may be operated to calibrate and testscales across a load range (e.g., across the entire rated load range ofthe scale).

In the illustrated construction, the force applying mechanism 306 isoperated automatically. In some embodiments, the force applyingmechanism 306 may be controlled manually (e.g., using physical controls(not shown) or virtual controls provided via the display 220). In theprovided example, the display 220 is used to select a weight/force to beapplied, and the force applying mechanism 306 may be adjusted to applythe selected force. In some embodiments, the display 220 may be externalto the electronic controller 105 and included in a second externalelectronic controller (e.g., a computing device such as a laptopcomputer, a tablet computer, a smart phone, a smart watch, etc.)communicatively connected (e.g., via a wireless connection) to theelectronic controller 105. In other embodiments, the system 100 may notcontain a display and the weight/force can be identified from a remotestorage medium and transmitted to the electronic controller 105.

FIG. 4 is a block diagram of the display 220 of the electroniccontroller 105 of FIG. 2 . The illustrated display 220 includes, amongother things, a user interface 405. In some embodiments, the display 220is a touch screen, and, in other embodiments, the display is controlledby a mouse and keyboard. In the example illustrated, the display 220 isintegrated within the electronic controller 105.

As noted, in some embodiments (not shown), the display 220 may beexternal to the electronic controller 105. When the display 220 isexternal, it may be part of a second electronic controller, such as amobile computing device. In such embodiments, the electronic controller105 is wirelessly connected to the second electronic controller. Inembodiments lacking a display, the input is predetermined within astorage medium and can be selected based upon attributes of the scale tobe calibrated.

The user interface 405 (e.g., a graphical user interface) allows usersto interact with the system 100 and, potentially, to specify targetvalues and gravity correction factors. The user interface 405 is notlimited to these features and may, in other embodiments, allow users toenter additional information.

FIG. 5 illustrates an example method 500 for calibrating a scale usingthe scale calibration device 110. In some embodiments, the method 500 isperformed by the electronic processor 205 and, in particular, theelectronic processor 205 executing the calibration engine 225.

At block 505, the electronic processor 205 determines a target forcevalue. For example, the target force value may be received from the userinterface 405. In another example, the target force value may bereceived from an external source.

In some embodiments, the target force value is based on a requestedtarget force value and a gravity correction factor. The gravitycorrection factor corrects for the gravity in the geographic locationwhere the calibration is occurring. In some embodiments, the gravitycorrection factor is provided via a user input. In other embodiments,the gravity correction factor is retrieved from a database or a remoteserver based on the location of the scale calibration device 110 (e.g.,as determined using an electronic geolocation system or provided via theuser interface 405).

Once the target force value has been received, the electronic processor205 determines a first value that is greater (e.g., by an amount, apercentage, etc.) than the target force value. For example, if thetarget force value is a force value that corresponds to 200 pounds ofweight, then the electronic processor 205 may determine the first valueto be a force value that corresponds to 210 pounds of weight. After thefirst value is determined, the electronic processor 205 controls theactuator 310 to apply a first applied force having the first value for afirst or “pre-load” interval of time (e.g., for 30 seconds) (block 510).

In some embodiments, after the target force value is received, apreliminary force value is used to control the actuator 310. Thepreliminary force value is a value substantially less than the targetforce and is used to confirm a user's desire to begin the calibrationprocess. The preliminary force is applied for a pre-calibration intervalto, for example, confirm that the user intends to initiate calibration,give the user a period of time to ensure that the scale to be calibratedis positioned properly and without interference (e.g., from a user'sclothing, appendages, other items, etc.). When the pre-calibrationinterval has expired, the actuator 310 is disengaged causing thepreliminary force to no longer be applied, and a user prompt requestinga confirmation command is displayed, via the user interface 405. In someembodiments, the pre-calibration interval is set to zero so the actuator310 moves into the disengaged/wait routine as soon as thepre-calibration force is achieved.

In some embodiments, the actuator 310 is disengaged by reversing themotor 307 (e.g., a stepper motor) to retract the actuator 310 until theload cell 315 indicates that no force is being applied. In someembodiments, the actuator 310 is disengaged by reversing the motor 307(e.g., a servo motor) to move the actuator 310 a predetermined distance(for example, 1116th of an inch). If a response to the user promptindicates an abort command, the actuator 310 is fully disengaged (e.g.,is fully retracted). In the response to a user prompt indicating aconfirmation, the calibration process continues.

In some embodiments, after the user confirmation is received, theelectronic processor 205 determines whether certain physical conditionshave changed before continuing with the calibration process. Forexample, the electronic processor 205 may be configured to determinewhether the scale has moved since the preliminary force was applied. Insome embodiments, the electronic processer 205 determines that the scalehas moved when the load cell 315 registers no increase in applied forceafter the actuator 310 engages for a threshold period. In someembodiments, the threshold period is based on amount of time that passedbetween the controlling the actuator to apply the preliminary force andthe load cell 315 registering the preliminary force.

In some embodiments (e.g., when the actuator is controlled to retract apredetermined distance, as noted above), the electronic processer 205determines that the scale has moved when the load cell 315 registers noincrease in applied force after the actuator 310 has moved apredetermined distance (for example, 118th of an inch) with no increasein the measured applied force. Whether measured using time or distance,the lack of measured applied force indicates that the actuator 310 iseffectively pushing against nothing, and, in response, the electronicprocessor 205 aborts the calibration process.

Upon the expiration of the first interval of time, the electronicprocessor 205 controls the actuator 310 to apply a second applied forcehaving a second value for a second or “calibration” interval of time(block 515). The second value is substantially equal to the target forcevalue (received at block 505) (i.e., as close as possible to the targetforce value, given the physical and electronic constraints of the scalecalibration device 110). In some embodiments, the second value is withinan acceptable tolerance of the calibration value (e.g., within fiveone-hundredths of a percent). The second interval is set to allow anoperator to run the calibration function of the scale being calibrated.In some embodiments, the second interval is indefinite and must be endedusing a user input.

In some embodiments, controlling the actuator 310 to apply the targetforce includes initially applying a force slightly different than (e.g.,below) the target force value and then adjusting (e.g., increasing) theforce to the target force value. For example, if the target force valueis a force value that corresponds to 200 pounds of weight, then theelectronic processor 205 may determine the second value to be a forcevalue that represents between 195 pounds and 199 pounds of weight. Insome embodiments, upon the expiration of the first interval of time, theelectronic processor 205 controls the actuator 310 to apply an appliedforce having a force value that is less than the target force value,after which the force is increased to the target force value over arelatively brief “loading” time interval (e.g., less than 5 seconds).

In some embodiments, the method 500 is repeated for a series of targetforce values across a calibration range. For example, a medical scalemay be calibrated at target force values of 100, 200, 300, and 400pounds.

In some embodiments, the electronic processor 205 operates to maintainthe applied force at or near the target force value using a hysteresisprocess. For example, during the calibration time interval (during whichthe target force is being applied), the electronic processor 205receives and analyzes an applied force value (from the load cell) forthe second applied force. When the applied force value is less than thetarget force value by a first threshold (e.g., 0.4 pounds), theelectronic processor 205 controls the actuator 310 to increase the thirdapplied force to the target force value. When the applied force value isgreater than the target force value by a second threshold (e.g., anamount (1 pound), a percentage of the target force value, etc.), theelectronic processor 205 controls the actuator 310 to reduce the thirdapplied force to the target force value.

As described, the first and second thresholds for the hysteresis processare different. In other embodiments, these thresholds may be the same ormay be reversed (e.g., the second threshold higher than the firstthreshold).

FIG. 6 illustrates an example user interface 600 generated by theelectronic controller 105 for display on the display 220. In the exampleshown, the user interface 600 is in a process of calibrating a scale anddisplays a target weight 605, to which the scale is being calibrated. Acurrent weight 610 that is being applied, as measured by the load cell315, is displayed. A gravity correction factor 615 displayed is set bythe user in a different user interface; however, in other embodiments,this can automatically be calculated based on a location determined viaautomated geolocation, as described earlier.

A group of completed status indicators 620 are configuration steps thatthe user has completed. A group of uncompleted status indicators 625 aresteps within the calibration process that user has not seen orcompleted. Upon completion of the example user interface 600, acalibration indication 630 will display green indicative of beingcomplete.

Although the status indicators 620 and 625 show a list of steps, thecalibration process in other embodiments may consist of more or fewersteps. In some embodiments, steps may be automated and will not needuser configuration. For example, the positioning and locationconfiguration steps may be automated and may not need manual userintervention.

FIG. 7 is a line graph illustrating an example rate of change per secondexperienced by the load cell 315 of the scale calibration device 110when the device 110 is configured to apply force immediately at thetarget value (i.e., without using the methods described herein). Asshown in FIG. 7 , the applied force drops at a rate of 17.5 pounds perminute for 20 seconds. In order to get a stable reading (e.g., anapplied force that oscillates within the rated accuracy for the scalebeing calibrated) for calibration purposes, the device 110 must beallowed to settle for approximately 130 seconds.

FIG. 8 is a line graph illustrating the rate of change per secondexperienced by the load cell 315 of the scale calibration device 110when the device 110 is configured to apply force using the methodsdescribed herein. As shown in FIG. 8 , the applied force drops onlyabout 1 pound and stabilizes within 30 seconds.

FIG. 9 is a line graph illustrating the rate of change per secondexperienced by the load cell 315 of the scale calibration device 110when the device 110 is applying force at the target value during thethird interval (as described above with respect to the method 500). InFIG. 9 , the device 110 is applying the hysteresis process describedabove. As shown in FIG. 9 , the applied force stabilizes almostimmediately and holds substantially at the target value indefinitely.

Thus, the invention may provide, among other things, systems and methodsfor automatically calibrating scales, such as, for example, medicalscales.

In the foregoing specification, specific embodiments have beendescribed. However, one of ordinary skill in the art appreciates thatvarious modifications and changes can be made without departing from thescope of the invention as set forth in the claims below. Accordingly,the specification and figures are to be regarded in an illustrativerather than a restrictive sense, and all such modifications are intendedto be included within the scope of present teachings.

One or more independent features and/or independent advantages of someembodiments may be set forth in the following claims:

What is claimed is:
 1. A system for calibrating a scale, the systemcomprising: a human machine interface; and an actuator configured toapply force to a platform of the scale to simulate placing a weight onthe platform; and an electronic processor communicatively coupled to thehuman machine interface and the actuator and configured to: (a)electronically control the actuator, to apply, for a first interval, afirst applied force to the platform, the first applied force having afirst value greater than a target force value representing an intendedcalibration force; and (b) electronically control the actuator to apply,for a second interval, a second applied force to the platform, thesecond applied force having a second value substantially equal to thetarget force value.
 2. The system of claim 1, wherein the electronicprocessor is further configured to control the actuator to apply thesecond applied force by: prior to applying the second applied force,controlling the actuator to apply a third applied force having a thirdvalue less than the target force value, and after controlling theactuator to apply the third applied force, controlling the actuator toincrease the applied force to the second value.
 3. The system of claim1, further comprising a load cell communicatively coupled to theelectronic processor and configured to measure the force applied by theactuator, and wherein the electronic processor is configured to, duringthe second interval, receive, from the load cell, an applied force valuefor the second applied force.
 4. The system of claim 3, wherein theelectronic processor is further configured to, when the applied forcevalue is less than the target force value by a first threshold, controlthe actuator to increase the second applied force to the target forcevalue.
 5. The system of claim 3, wherein the electronic processor isfurther configured to, when the applied force value is greater than thetarget force value by a second threshold, control the actuator to reducethe second applied force to the target force value.
 6. The system ofclaim 1, wherein the electronic processor is further configured todetermine a plurality of target force values, and repeat acts (a) and(b) for each of the plurality of target force values.
 7. The system ofclaim 1, wherein the electronic processor is further configured todetermine a location for the scale, and retrieve, from an electronicmemory, a gravity correction factor based on the location, and whereinthe first value and the second value are determined based on the gravitycorrection factor and the target force value.
 8. The system of claim 1,wherein the electronic processor is configured to before proceeding withact (a), control the actuator to apply, for a pre-calibration interval,a preliminary applied force having a preliminary value.
 9. A system forcalibrating a scale, the system comprising: a human machine interface;and an actuator configured to apply force to a platform of the scale tosimulate placing a weight on the platform; and an electronic processorcommunicatively coupled to the human machine interface and the actuatorand configured to: (a) electronically control the actuator, to apply,for a first interval, a first applied force to the platform, the firstapplied force having a first value greater than a target force valuerepresenting an intended calibration force; and (b) during the firstinterval, receive, from a load cell, an applied force value for thefirst applied force; and (c) when a rate of change of the applied forcevalue passes a rate of change threshold, determine an end of the firstinterval.
 10. The system of claim 9, wherein the electronic processor isfurther configured to control the actuator to apply the second appliedforce by: prior to applying the second applied force, controlling theactuator to apply a third applied force having a third value less thanthe target force value, and after controlling the actuator to apply thethird applied force, controlling the actuator to increase the appliedforce to the second value.
 11. The system of claim 9, further comprisinga load cell communicatively coupled to the electronic processor andconfigured to measure the force applied by the actuator, and wherein theelectronic processor is configured to, during the second interval,receive, from the load cell, an applied force value for the secondapplied force.
 12. The system of claim 11, wherein the electronicprocessor is further configured to, when the applied force value is lessthan the target force value by a first threshold, control the actuatorto increase the second applied force to the target force value.
 13. Thesystem of claim 11, wherein the electronic processor is furtherconfigured to, when the applied force value is greater than the targetforce value by a second threshold, control the actuator to reduce thesecond applied force to the target force value.
 14. The system of claim9, wherein the electronic processor is further configured to determine aplurality of target force values, and repeat acts (a) and (b) for eachof the plurality of target force values.
 15. A non-transitorycomputer-readable medium including instructions executable by anelectronic processor to perform a set of functions, the set of functionscomprising: (a) receiving a user input via a human machine interface,the user input including a target force value representing an intendedcalibration force; (b) in response to receiving the user input,electronically controlling an actuator, to apply, for a first interval,a first applied force having a first value greater than a target forcevalue, wherein the actuator configured to apply force to a platform ofthe scale to simulate placing a weight on the platform; (c)electronically controlling the actuator to apply, for a second interval,a second applied force having a second value substantially equal to thetarget force value; and (d) when the second interval has expired,electronically disengaging the actuator.
 16. The non-transitorycomputer-readable medium of claim 15, wherein controlling the actuatorto apply the second applied force includes, prior to applying the secondapplied force, electronically controlling the actuator to apply a thirdapplied force having a third value less than the target force value. 17.The non-transitory computer-readable medium of claim 15, wherein the setof functions further comprises: during the second interval, receiving,from a load cell, an applied force value for the second applied force;when the applied force value is less than the target force value by afirst threshold, electronically controlling the actuator to increase thesecond applied force to the target force value; and when the appliedforce value is greater than the target force value by a secondthreshold, electronically controlling the actuator to reduce the secondapplied force to the target force value.
 18. The non-transitorycomputer-readable medium of claim 15, wherein the set of functionsfurther comprises: determining a location for the scale; retrieving,from an electronic memory, a gravity correction factor based on thelocation; and wherein the first value and the second value aredetermined based on the gravity correction factor and the target forcevalue.
 19. The non-transitory computer-readable medium of claim 15,wherein the set of functions further comprises: in response to receivingthe user input, electronically controlling the actuator to apply, for apre-calibration interval, a preliminary applied force having apreliminary value; when the pre-calibration interval has expired,disengaging the actuator; and displaying, via the human machineinterface, a user prompt requesting a confirmation command beforeproceeding with act (b).
 20. The non-transitory computer-readable mediumof claim 15, wherein the set of functions further comprises: during thefirst interval, receiving, from a load cell, an applied force value forthe first applied force; and when a rate of change of the applied forcevalue passes a rate of change threshold, determining an end of the firstinterval.